border-bottom-1px($color)
  position relative
  &::after
    display block
    position absolute
    left 0
    bottom 0
    width: 100%
    border-top: 1px solid $color
    content ' '

border-top-1px($color)
  position relative
  &::after
    display block
    position absolute
    left 0
    top 0
    width: 100%
    border-top: 1px solid $color
    content ' '

border-left-1px($color)
  position relative
  &::after
    display block
    position absolute
    left 0
    top 0
    height: 100%
    border-left: 1px solid $color
    content ' '

border-none()
  &::after
    display none
    border 0

bg-image($url)
  background-image: url($url+"@2x.png")
  @media (-webkit-min-device-pixel-ratio: 3),(min-device-pixel-ratio: 3)
    background-image: url($url+"@3x.png")
